Threading Performance of Different Coatings for High Speed Steel Tapping

Round 1

Reviewer 1 Report

This is an interesting and applied work that fits well within the scope of this Journal. My comments/suggestions are given hereafter:

1. Introduction: You mention that TiCN has higher toughness. Do you mean fracture toughness?
2. Introduction: You mention that you are interested in coatings with ‘better lubrication properties’ that ‘at the same time support adhesion phenomena’. Would you actually want to avoid adhesive wear, as it can initiate localized sticking and thus degrade your frictional properties?
3. Could you please provide more information on the coatings that you investigated?   
4. In your results you mention that higher torque values affect the tool life. However, your wear tests show otherwise. Sometimes in tribology wear and friction (torque in this case) do not correlate. Can the higher torque values be due to different wear mechanisms or to differences in the dimensional tolerance of taps and treads?
5. Add scale in Figure 11
6. In your results you mentioned that TiAlN and TiAlN+WC/C have 75% less wear than TiN and uncoated samples. TiN coatings are not the same as uncoated, so it must be 75% from one of the two. Furthermore, their values are not 75% less, but 25% less than your reference (your measured values are 75% of the reference).
7. This is nice work, but what is missing from my point of view is the ‘why’ you are observing those differences from a ‘materials-microstructure’ point of view. For example, do you have the same wear mechanism with all your coatings and reference (uncoated)?
8. Small English and grammar check required. For example ‘In this work was tested coatings of …’ → ‘In this work coatings of … were tested’ etc.   

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

1. The studies on different types of coatings should be reviewed to extend the literature review section:

Microstructure, Mechanical, Oxidation and Corrosion Properties of the Cr-Al-Si-N Coatings Deposited by a Hybrid Sputtering System, Coatings.

Tribological properties, oxidation resistance and turning performance of AlTiN/AlCrSiN multilayer coatings by arc ion plating. Surface and Coatings Technology

Effect of nitrogen partial pressure on microstructure and mechanical properties of Mo-Cu-V-N composite coatings deposited by HIPIMS. Surface and Coatings Technology

2. What are “go” and “no-go”, the authors should present a clear definition in the manuscript.
3. Why the authors selected 50 m/min as the cutting speed? How about the feed rate?
4. The authors investigated the lubrication of the tools with different coatings. Besides torque, the friction coefficient between the cutting tool and workpiece is an important indicator, and it is suggested to calculate the coefficients when use different tools. Referring to “Wear mechanisms and performance of abrasively ground polycrystalline diamond tools of different diamond grains in machining titanium alloy, Journal of Manufacturing Processes”
5. The authors discuss about the tool life, the reviewer appreciate the Fig.12 which shows the tool wear at different tooth. However, there are still some detailed information need to be provided. What is the criteria of the tool rejection for tapping (according to any ISO standard)? Still use the development of VB (flank wear landing)? Please provide the judgement of tool wear development referring to “Performance and wear analysis of polycrystalline diamond (PCD) tools manufactured with different methods in turning titanium alloy Ti-6Al-4V, International journal of advanced manufacturing technology”
6. Please add discussions about the machined threads with different taps.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors,

 

I read your contribution with interest and attention. I can surely say that there are several remarkable points for reflection and, in general, that the article is valid. At the same time, I have to say that there are several issues that require correction or explanation.

My suggestions are listed without priority but I hope they all contribute to allow a general improvement of the work

1. Consider rewriting the sentence (page 1): “The reason for the relative absence of manuscripts which analyze this operation is due to the high complexity of the operation implies that the models carried out often are not successful due to this complexity.”
2. Page 3, “[…] in Pereira and da Silva forming […] were the most robust [14]” consider “[…] in Pereira and da Silva forming [14]”. The same in case: “[…] Elósegui et al.”, “[…] in Abdoos et al”, “[…] Bezerra and Coelho”, etc.
3. Figure 1, in my opinion is too dark, I suggest to provide brighter photo with slightly different perspective, which shows the outline of drilled holes.
4. Page 4, “[…] with a 10º inlet cone half angle”, consider “[…] with a 10˚ inlet cone half angle”.
5. Page 4, Figures 2 and 3, photos are out of focus, consider replacing it.
6. Page 5, “although the number 3.1 Tap (Table 1) has not”, change to “although the number 3.1 Tap (Table 2) has not”.
7. Page 6, “results collected in Table 1” change to “results collected in Table 2”
8. Page 7, consider placing section 3.2, before Table 2. describe the measuring method before the results.
9. Page 7, “This torque is known to be sensitive to the tap wear status.”, reference is needed.
10. Page 7, provide the information about how the monitoring system presented in Figure 6 was calibrated
11. Page 7, “sensitive to the thread quality [17]”, consider , “sensitive to the thread quality [17]” – delete bold from reference.
12. Page 8, there is no “pre-drilled hole” included in Figure 8.a (i) and (ii).
13. Page 10, I thing that additional figure depicting where the teeth are would be helpful.
14. Page 12, Figure 13.c, the wear [%A] in case of TiCN is lower than in case of TiAlN. It would be nice if the Authors describe the possible reason of this, even marginally, in the work.
15. Page 13, Figure 14 and 15, what does Thread 1,2 etc. means. Please explain.
16. Page 14, what is the possible reason of such large differences in wear for TiAlN#5,4,3 and TiAlN#1,2, and therefore in standard deviation in Figure 17. Isn’t it due to the difference in tap geometry in the 10-12 tooth range? Authors should try to explain the possible reason of this.

Kind regards

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

A very written structured analysis of the wear of coatings used on tapping tools.

The reviewer would like to know the following:

1. Is there a particular reason why this work was performed/commissioned?
2. What tests did you perform to characterize the integrity of the coatings before you began the experiments?
3. Did you conduct a failure analysis of the coatings after the tests performed? May we see that analysis?
4. Why did you not perform tool life experiments in accordance with the ISO standards?
5. Is it possible to include answers to these questions in your updated manuscript?

A minor spell check is required prior to re-submission.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Accept in present form

Reviewer 4 Report

Acceptable in present form